To see where hydrogen is a molecule, click the back arrow button . To see where hydrogen is in the form of ions, click the forward arrow button.

The false-color
image to the left, created by the NRAO 140 FT telescope in Green Bank,
shows where one can find hydrogen atoms
toward Orion. The regions with the most atoms are red. The white
regions to the left is where we don't have observations with the 140 FT.

Most of the interstellar gas
is hydrogen and most of the hydrogen is in the form of atoms. Thus,
astronomers study atomic hydrogen to find out the properties of a good
portion of the interstellar gas.

Hydrogen can also be in the form of molecules
or ions. If a region of gas is hot enough, molecules can be destroyed and then become atoms or ions. Or, if a region cools then molecules might form from the atoms.

To continue the tour, click the
right arrow button; to go back in the tour, click the left arrow button .